OOh, I'm so jealous of pimpin' out a PC like that! I know a few people who will get mad at me for saying this, largely because I am part of the "save you're money and use a boring ol' black box" school of thought, but for these kind of changes, I can make an exception.
The images look great, naturally, but if I were painting my computer, I would only paint one side (as one would be placed against a desk or whatever and won't be seen), and perhaps I would pain the entire box a uniform color that will blend in with the image.
For example, have the entire box be the dark blue of the night sky if using the first image, or a pale yellow if using the second image. I think the blue will work nicer in the end, but then again, this is not my computer.
These are after all only suggestions.